Nosey Potter will know. If you google hypertuffa then that medium is easy to work with.

Yes - Nosey made some beautiful ones.

I agree, Noseypotter is definitely the one to help you. Have a look at some of his sculptures that he's done in concrete, they're awesome. I'm sure that he won't mind if you PM him for advise.

He hasn't been around much lately - am a bit concerned about him. Hope he answers you as he's definitely the one to ask.

He hasn't been well - he did blog at the end of June. I think he'd been in hospital. He said he was getting better, so I hope he's ok.